1. Field of the Invention
The present invention relates to a folding knife with safety for blade, and more particularly to a folding knife with a safety for blade mounted on a handle of the knife, so that the safety for blade can be conveniently operated with only one finger to lock the blade in place after the blade has been extended from the handle or folded into the handle.
2. Description of Prior Art
Generally, a knife with one or more folding blades employs an inclined leaf spring as a,blade lock. When a knife blade is rotated into a fully open position, the leaf spring presses against a rear end surface of the blade to prevent the blade from moving. To close the blade, the leaf spring is depressed so that it no longer presses against the rear end of the blade and thereby allows the blade to rotate into a folded position in the knife handle.
When a user uses a pointed front end of such folding blade on a knife to, for example, cut a hole on something, and the blade is subject to a large vertical force or large recoil, it is very possible the leaf spring disengages from the blade due to an overly large force applied on it, resulting in an unexpectedly closed blade to injure the user.
U.S. Pat. No. 5,596,808 entitled "Safety for Blade Lock" discloses a knife having a folding blade, a blade lock in the form of a leaf spring, and a safety for preventing unlocking of the lock. The safety has an elongate arm mounted on the knife handle. A stud is positioned on an inside surface of one end of the arm. A contact surface is formed on an outside surface of the arm opposite from the stud. The other end of the arm is pivotably attached to the handle of the knife. The arm may be swung from a release position, unobstructive of the lock, to a safety position in which the presence of the stud prevents unlocking the lock. And, the arm may be spring biased toward the release position allowing a user to move the blade into a folded position in the handle.
The safety for blade lock disclosed in U.S. Pat. No. 5,596,808, either in the form of an elongate arm, a slide or a rotating disk, requires the stud to press against a lateral side of the blade lock. In the event there is any defect in the structural design of the folding knife, or the blade of the folding knife is not sufficiently pivotally tightened to the handle, or a clearance between the blade lock and the stud increases due to wearing after the folding knife has been used for a long time, the blade lock tends to lose its safety effect.
Moreover, either the folding knife disclosed in U.S. Pat. No. 5,596,808 or other general folding knives do not have any other safety designed to prevent possible separation of a blade in the folded position from the handle due to serious vibration or dropping from a high position. Therefore, it is desirable to develop a safety for blade that can be easily operated to safely hold an extended or folded blade in place.